Oil-bath air cleaner



y 1950 o. c. R. LEE ETAL 2,509,510

OIL BATH AIR CLEANER Filed Aug. 1, 1945 WWW WW1] Attorney Patented May 30, 1950 UNITED STATES PATENT OFFICE Application August 1, 1946, Serial No. 687,792 In Great Britain December 10, 1943 4 Claims. 1

A well known type of gas filter or cleaner includes means by which the gas to be cleaned is caused to impinge upon a liquid surface and to be cleaned by passing through liquid spray or mist, generally as it passes under a lip or rim extending down to a level more or less approximating to the surface level of the liquid. In many cases the liquid used is oil and these cleaners are known as oil bath cleaners; this term is used herein without implying that the liquid to be used is necessarily oil. As the gas rises away from the surface it carries oil mist or spray with it and a scrubbing stage of cleaning follows in an oil-wetted scrubber.

So long as the fiow is substantially constant, the level at which the lip or rim should lie relatively to the oil surface level (i. e. the level to which the bath is filled) to give the best results can be determined. It has however been found that where there is considerable variation of gas flow the carry-over of oil tends to become excessive at maximum volume of flow if the scrubber is to be efiiciently wetted at (say) half that volume of flow. This tendency is increased by tilting or splashing if the cleaner is carried on a tank or other vehicle.

In a co-pending specification, Number 536,788, there has been proposed the provision of means dependent upon the volume of gas flow to vary the height of the lip or rim relatively to the oil surface level, in order to minimise or avoid excessive carry-over. In the typical example described in that specification the bottom edge of an open bottomed piston like member forms the lip or rim and the arrangement is designed to cause the member to rise or fall according to the volume of gas flowing. Suggestions have also been made for utilising the pressure drop through a filter pad or the like incorporated in the oil bath cleaner to vary the oil level under the lip relatively to that in a central oil storage space subjected to the lower pressure. Such arrangements are dependent upon the filter pad or the like maintaining its original characteristics (and not becoming more resistant because of partial clogging of the pores or the like) if the relationship between flow and oil level is to remain, in use, as originally determined. Moreover, as is well known, in the normal internal combustion engine, depression becomes less in the induction pipe (or equivalent position between the throttle valve and the engine intake as will be understood when the induction pipe or its depression are referred to) as the throttle is opened and air flow increased. From one aspect the present inven- 2 tion takes advantage of this fact to raise the oil level relatively to the lip or rim of an oil bath cleaner when the engine induction pipe depression increases and to lower it when it decreases.

From another point of view the invention provides an independent control unit for a cleaner of the oil bath type which can itself be of substantially normal form and without moving parts.

Other parts of the invention are embodied in a typical example which will now be described with reference to the accompanying drawing which is a central sectional elevation.

At the right of the figure there is shown a more or less conventional combined oil bath cleaner and air filter attached to the induction pipe I fitted with a butterfly throttle valve 2 of an internal combustion engine. The air outlet pipe 3 of the combined filter and cleaner is clipped or otherwise conventionally attached to the pipe I. Upon a flange 4, with an intermediate joint ring 5, rests the lower rim of a spigot portion 6 of the outer casing 1. This casing has an outwardly sloping bottom I which terminates in an annular channel of appropriate depth and shape to form the oil well 8. Supported on the bottom 7' of the casing I, with an intermediate joint ring 9, is a tubular member ID which carries a conventional oil scrubber (formed for example of a pack of metal wool II supported between perforated plates I2) and the bottom end plate I3 of an oil-wetted filter. This filter is shown of well known form comprising a star-shaped element of fabric I 4 supported by metal gauze I5 secured between end plate I3 and an upper end plate I6. The domed cover I! is welded to a cylindrical part I8 provided with an internal flange l9 which rests on the scrubber. The lower end of the part I8 is extended to form the lip 21) over the annular oil well 8. A spider 2| at the top of the outlet pipe 3 carries a securing screw 22 which passes through the cover I1, so that the assembly is retained by a wing-nut 23, a spring 2 bearing on the upper end cover I6 serving to maintain the assembly of the oil-wetted filter.

' The main feature of all this structure, so far as the present invention is concerned, is the annular oil well 8 into which oil from the scrubber will drain back down the sloping bottom I. The path of the air to the engine is, as indicated by the arrows, down between the walls 1 and I8 to impinge on the surface of the oil in the oil well 8, up through the scrubber, in through the star shaped oil wetted filter element, and. down through the pipe 3 to the engine induction pipe I. The well 8 is connected by a pipe 25 to the independent oil level control device shown at the left of the drawing. This consists of a main cylinder 26 containing a given quantity of oil, and a piston 21 (shown of conventional form in cluding oppositely facing cup washers) which bears on the surface of the oil. Attached to piston 21 is a sub cylinder 28 which contains a return spring 29 and a fixed piston 30. The piston 30 is attached to the top of a stand tube 3| mounted centrally in the main cylinder 26. The stand tube 3! is connected by pipe 32 to the source of the controlling suction-in this case the engine induction pipe. For convenience in filling and in case of oil leakage past the piston 21 pipes such as 32, 33 may be fitted.

The operation will be apparent. At small engine throttle openings, the high depression obtained in the induction pipe l causes the sub cylinder 28and thus the main piston Zl-to be drawn in a downward direction thereby forcing the oil out of the cylinder 26 into the oil well 8 of the cleaner/so raising its level.

As the engine throttle 2 is opened and the depression in the induction pipe 5 decreases the return spring 29 raises the sub cylinder 28, and thus also the main piston 21 so drawing oil from the cleaner Well, and consequently lowering the level.

It will be clear that the oil level in the cleaner is raised or lowered in relation to the depression existing in the engine induction pipe, so giving a high oil level at small throttle openings (1. e. low air flow) and a corresponding lower level as the throttle opening increases (i. e. higher air flow).

Obviously similar action can be obtained by means of an appropriate device of the nature of a flow meter; and appropriate shaping of the oil well 8 and proportioning of the parts (and strength of the return spring) of the control unit will give just the desired variation of level.

We claim:

1. In combination, an intake pipe for an internal combustion engine, a throttle valve in said intake pipe, an air cleaner having an oil bath and connected to said intake pipe and in communication with said intake opening, and means connected to said intake pipe on the engine side of said throttle valve and responsive directly to depression in said pipe for varying the oil level of said bath in said cleaner in accordance with air volume requirements, whereby relatively high deair cleaner, comprising a cylinder adapted to be filled with oil, a pipe in communication with and extending from said cylinder for connection with the oil well of the air cleaner, a piston movable in the cylinder, an inverted sub-cylinder carried by the piston, a fixed piston carried by said cylinder and operatively fitting said sub-cylinder, a pipe connection through the fixed piston and adapted to connect the sub-cylinder to a suitable source of suction, and a spring in opposition to the action of said suction for returning said sub-cylinder and movable piston to a normal position, whereby relatively high depression due to small throttle openings will create a relatively high oil level in the cleaner well and vice versa.

3. Apparatus for varying the level of the oil bath in an oil bath type of air cleaner which is connected with the air induction pipe of an internal combustion engine, comprising a closed container adapted to be filled with oil, a passage opening from said container for communication with the oil well in the air cleaner, and means for varying the pressure in said container to transfer oil between said container and the cleaner oil well in accordance with the depression from the engine in the induction pipe, whereby relatively high depression due to small throttle openings will create a relatively high oil level in the cleaner oil well and vice versa.

4. An oil level control unit for an oil bath type air cleaner, comprising a cylinder adapted to be filled with oil, a passage in communication with said cylinder and for communication with the oil well in the air cleaner, a piston movable in said cylinder and means operative to move said piston and responsive to a source of suction that is variable in accordance with the air volume demands on the air cleaner to actuate said piston to vary the quantity of oil in said cylinder and the oil level in the cleaner oil well.

DAVID COLIN ROCLIFFE LEE. ERIC MAXIMILLIAN BOSSON. CECIL GORDON VOKES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Nov. 28, 1945 

